The Cornell Putnam page offers more information on all the math competitions offered throughout the year. In the fall semester, they run weekly practice sessions. Cornell also holds a math modeling competition, the CMCM, in October every year. There are also several community outreach opportunities, where undergraduates can tutor or help with educational events for K-12 students. The math department seminar bulletin gives a schedule of all upcoming talks, seminars, and colloquia. This list has links with more information on each series.